JPS6156507B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for processing a planographic material that does not require dampening water,
In particular, it is characterized in that the printing plate is entirely exposed to actinic rays through a protective film to the extent that image formation is not affected. A lithographic plate that does not require dampening water and has a photosensitive image forming layer and a protective film provided in this order on a silicone rubber layer lined with a substrate is known, for example, as disclosed in Japanese Patent Application Laid-open No. 1983-1999.
No. 82402, No. 50-66304, No. 50-161305, No. 51-8003
Some proposals have been made for the issue. JP-A-49-82402 proposes the use of a polyolefin film as the protective film. Also, JP-A No. 50-66304, 50-
No. 161305 and No. 51-8003 propose the use of polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyethylene terephthalate, cellophane, etc. as the protective film. However, a lithographic plate material that does not require dampening water and has a photosensitive image forming layer and a protective film provided in this order on a silicone rubber layer backed by a substrate has the following problems. First, it is very difficult to uniformly coat a photosensitive layer on a silicone rubber layer, so it is possible to bond a protective film coated with a photosensitive layer uniformly to a silicone rubber layer backed by a substrate. Alternatively, it is necessary to manufacture the planographic material by coating a protective film with a photosensitive layer and then bonding the film coated with a silicone rubber layer to a substrate. However, the photosensitive layer coated on the protective film is
Since it is necessary to form an extremely thin film, preferably about 0.5 to 10 μm, it is necessary to use a dilute photosensitive layer composition solution for coating. It is very difficult to coat protective films with relatively low surface tension, such as polyolefin in-films, as they may cause repellency. For reference, the critical surface tensions of various films are shown in Table 1.

【table】

[Table] On the other hand, it is easy to coat a film having a relatively high surface tension such as polystyrene or polyethylene terephthalate with a dilute solution of the photosensitive layer composition, but the following problems also occur in this case. That is, if a protective film with relatively high surface tension is used as a protective film to improve the coating suitability of the photosensitive layer and a lithographic plate material that does not require dampening water is manufactured in the same way, the adhesion between the protective film and the photosensitive layer of the plate material will be reduced. is too strong, and when the protective film is peeled off before or after normal pattern exposure, a phenomenon occurs in which the photosensitive layer is also attached to the protective film. JP-A No. 50-66304 utilizes this phenomenon to adhere the photosensitive image forming layer in the exposed area to the silicone rubber layer, and then peels the remaining part together with the protective film between the silicone rubber layer and the photosensitive layer and removes it. Although the possibility of peeling development is mentioned, this method also cannot completely reproduce fine halftone dots, thin lines, etc., and requires additional development using a solvent or the like. As a result of intensive studies to improve these problems, the inventors of the present invention found that when a protective film is exposed to actinic rays for a short period of time, the adhesive force between the protective film and the photosensitive image forming layer changes significantly. As a result, the protective film can be peeled off very easily, and when the irradiation with actinic rays is extremely short, the change does not reach the bottom of the photosensitive image forming layer (the side in contact with the silicone rubber layer), which prevents image formation. The present invention was achieved by discovering the surprising fact that there is no effect. That is, the present invention improves the coating suitability of a dilute solution of a photosensitive image forming layer composition by using a protective film having a relatively high surface tension such as a polystyrene film or a polyethylene terephthalate film, and protects the print by exposing it to actinic rays. Taking advantage of the remarkable change in the adhesive strength between the film and the photosensitive image forming layer, the lithographic material can be prepared in advance to the extent that image formation by pattern exposure is not affected even if a protective film with a relatively high surface tension is used. This is a method for processing planographic materials that does not require dampening water and makes it easier to remove the protective film by exposing the entire surface to light. The substrate used in the present invention has a thickness of approximately 10 μm.
~5 mm, preferably about 50 to 500 micron paper, plastic film or sheet, metal plate, or those provided with an adhesion improving layer with a silicone rubber layer are suitable, although cylindrical substrates may also be used. The silicone rubber layer used in the present invention is typically about
It has a thickness of 0.5 to 100 μm, preferably about 0.5 to 10 μm, and is mainly composed of a linear organic polysiloxane having a molecular weight of several thousand to several hundred thousand and having the following repeating units. Here, R is an alkyl group having 1 to 10 carbon atoms or a phenyl group, and preferably 60% or more of R is a methyl group. Such a linear organic polysiloxane can be sparsely crosslinked to form a silicone rubber by adding an organic peroxide and subjecting it to heat treatment. A crosslinking agent is also added to the silicone rubber layer. Crosslinking agents used in so-called room temperature (low temperature) curing silicone rubber include acetoxysilane, ketoxime silane, alkoxysilane, aminosilane, amidosilane, etc., and are usually linear organic polysiloxanes with hydroxyl groups at the ends. In combination with these, each deacetic acid type,
It becomes deoxime type, dealcoholized type, deamined type, and deamidated type silicone rubber. Generally, a small amount of an organic tin compound or the like is further added as a catalyst to these silicone rubbers. The protective film used in the present invention has a thickness of about 5 to 200μ, preferably about 10 to 80μ, and can be made of many types of films such as polyethylene terephthalate, polyvinyl chloride, polyvinylidene chloride, polystyrene, polycarbonate, nylon, and polyimide. However, it is also possible to use a film whose surface has been subjected to electrical discharge treatment, roughening treatment, etc. to improve wettability, such as a polyolefin film having a relatively low surface tension. The photosensitive image forming layer used in the present invention has a thickness of about 0.1 to 50 μm, preferably about 0.5 to 10 μm, and can be made of known photosensitive materials, but may have the following configuration: Appropriate. (1) Unsaturated monomers or their oligomers and photosensitizers with a boiling point of 100°C or higher and nonvolatile at room temperature,
A composition comprising a thermal polymerization inhibitor and, if necessary, fillers and some additives to provide shape retention at room temperature. Examples of unsaturated monomers include ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, glycidyl(meth)acrylate, and 1-chloro-2-hydroxyethyl( A series of acrylic esters such as meth)acrylate, dimethylaminoethyl (meth)acrylate, methacrylic esters, acrylamide derivatives such as ethylenebisacrylamide, N-methylolacrylamide, methoxymethylacrylamide, triallylcyanurate, triallylphos Esters of allyl alcohol such as phate, diallyl phthalate, diallyl maleate, other styrene derivatives,
Cinnamic acid derivatives and the like can be used. As photosensitizers, benzophenone derivatives,
Benzoin derivatives, anthraquinone derivatives, aldehydes, ketones, sulfur compounds, halogen compounds, or dyes such as methylene blue and riboflavin can be used. As thermal polymerization inhibitors, hydroquinone derivatives, phenol derivatives, nitro-substituted benzene,
Tertiary amines and phenothiazine derivatives are used. As fillers or additives, colloidal silica, calcium carbonate, magnesium carbonate,
Fine powder of inorganic substances such as iron oxide, polyvinyl acetate, poly(meth)acrylic acid ester, polyethylene with a molecular weight of several thousand, polypropylene, polyvinyl chloride, vinyl polymers such as polyvinylidene chloride, resol phenol before curing, urea Examples include melamine-based, epoxy-based, unsaturated polyester-based resins, etc. (2) Photocurable diazo resin or azide resin and if necessary a photosensitizer and some filler additives. Examples of the photocurable diazo resin include condensates of formaldehyde and diazo amines such as paradiazophenylamine, paradiazomonoethylaniline, and paradiazobenzylethylaniline. Examples of the photocurable azide resin include azidophthalate ester of polyvinyl alcohol, azidobenzoate ester, ester of styrene-maleic anhydride copolymer, and aromatic azido alcohol such as β-(4-azidophenol)ethanol. can be given. As photosensitizers, fillers, and additives, those listed in example (1) can be used. The conditions for the entire surface exposure in the present invention are appropriately set depending on the composition of the photosensitive image forming layer, the properties of the protective film, etc. For example, when a composition consisting of unsaturated monomers, fillers, photosensitizers, etc. is used as the photosensitive image forming layer, the thickness of the photosensitive image forming layer, the amount of photosensitizer added, the protective film The overall exposure conditions will vary depending on the nature of the image. Furthermore, even when irradiating the same amount of light, the overall exposure conditions may differ slightly depending on the light intensity. Therefore, the conditions for full-face exposure in the present invention are conditions that ensure good removability of the protective film and do not affect image formation.However, considering the efficiency of plate manufacturing, plate-making work, etc. is about 1 to 20 seconds, preferably 1 to 20 seconds.
The exposure intensity, the composition of the photosensitive layer, and the type of protective film should be selected so that the process can be completed in about 10 seconds and the effects of the present invention can be exhibited. It goes without saying that full-surface exposure is effective even if it is carried out before pattern exposure or before peeling off the protective film after pattern exposure. Example 1 Polyester film “Lumirror” manufactured by Toray Industries, Inc.
(Thickness: 12μ) A photosensitive image forming layer having the following composition was spin-coated to a dry thickness of 1.5μ. (a) 55 parts of a 20/70/10 copolymer of methyl methacrylate, ethyl acrylate and acrylic acid (b) 40 parts of an adduct of 1 mole of xylylene diamine and 4 moles of glycidyl methacrylate (c) Mr. Michler's ketone 0.5 During coating, a photosensitive layer solution with a solid content of 2% was used, and the coating properties were very good. Next, apply SH-781 manufactured by Toray Silicone Co., Ltd. on top of this.
A 10% solution of Isopar E (manufactured by Etsuso) was applied by spin coating. On the other hand, a 300μ thick chemically treated aluminum plate made by Sumitomo Light Metals is coated with a layer of vinylite made by Sanwa Vinyl Industries Co., Ltd. and a silane coupling agent SH made by Toray Silicone.
A substrate provided with a thin layer of -6020 was press-bonded to the above film. Store this item for 3 weeks and remove the protective film at 180℃.
A peel test was conducted. The results are shown in Table 2.

【table】

[Table] As a result, the peel strength of this lithographic plate material varies greatly over the entire surface exposure time range of 5 to 10 seconds. For example, in the plate exposed for 15 seconds, the peeling strength of the protective film is extremely poor. It can be seen that the image quality is good and the image reproduction performance of the plate is not impaired. Using this plate, the entire surface was exposed for 15 seconds, followed by pattern exposure using a negative type original image, the protective film was peeled off, and development was performed by immersion in isopropyl alcohol to obtain a lithographic plate material that did not require dampening water. Comparative Example 1 When the plate material of Example 1 was subjected to pattern exposure in the same manner as in Example 1 without being exposed to light over the entire surface, and when the protective film was attempted to be peeled off, the peeling was very heavy, the film was torn, and the protective film was not fully exposed. It could not be peeled off. Example 2 The plate material of Example 1 was subjected to pattern exposure in the same manner as in Example 1 without being exposed to light over the entire surface, and then the entire surface was exposed for 15 seconds and the protective film was peeled off.
The releasability was good, and when developed with isopropyl alcohol, a good planographic material that did not require dampening water was obtained.

Claims (1)

[Claims] 1. A lithographic plate that does not require dampening water and has a photosensitive image forming layer and a protective film provided in this order on a silicone rubber layer backed by a substrate, characterized in that the entire surface of the protective film is exposed to actinic rays. Processing method for planographic material that does not require dampening water.